Study on Sensitivity of Uncertainty Factors in Seismic Demand Analysis of Continuous Girder Bridges with Seismic Isolation Design

In order to clarify the influence of the uncertain parameters of a bridge numerical model for seismic isolation design on the calculation results of structural seismic demand and to improve the accuracy of bridge seismic isolation design, a refined numerical model of a seismic isolation continuous girder bridge was established. The uncertainty of the model parameters was sorted out at two classification levels of the seismic isolation device system and the non-isolated system, and the sensitivity of the structural parameters was systematically analyzed by using the tornado diagram and the first-order second-moment method. The uncertain factors that have a great influence on the seismic response of the bridge structure in the seismic isolation design are bulk density coefficient, bearing friction coefficient, clay ultimate resistance, damping ratio, elastic modulus, clay ultimate deformation, and isolation bearing fusing force. The impact of the seismic isolation bearing’s melting force is particularly significant during periods of low peak acceleration. It was observed that the selection results remained largely unchanged despite the consideration of the collision effect. This finding serves as a valuable reference for the design and calculation of seismic isolation measures in continuous beam bridges.